1. Field of the Invention
This invention relates generally to an improvement in the collection of solar energy for conversion into electricity for use in space and more particularly, but not by way of limitation, to an arrangement utilizing a plurality of solar radiation concentrating collectors that direct collected solar radiation by a low loss power bus to a centralized converter for conversion into electricity.
2. Description of the Invention
The use of dynamic converters in space has been proposed as a means of improving the efficiency of conversion of sunlight into electricity. Economies of scale that are needed in the turbogenerators that are used to convert heat into electricity have led to the use of centralized heat receivers that are fed by large concentrating collectors that are approximately twenty to thirty meters in diameter. If a single large concentrating collector is used then it must be capable of being segmented and folded into a compact package for stowing in a suitable launch vehicle for launch into space.
Such collectors also have difficulty in attaining the required accuracy for achieving a high concentration ratio. Such a high concentration ratio is needed to minimize the entrance aperture size and thus the level of re-radiation loss at the heat receiver. An upper limit of approximately 1000 for a concentration ratio has been postulated. Research performed by J. M. Cariou, et al, for the French National Solar Research Center has demonstrated the transmission of concentrated solar flux through single optical fiber strands. In their experiment, they collected concentrated sunlight from six small parabolic dishes and transmitted the power to a simple enclosed furnace. Their results included achieving a furnace temperature of 600 degrees C. with a total power of only 9 watts collected.
Analytical work performed by Daisuke Kato and Takashi Nakamura at the Electrotechnical Laboratory of the Japanese Ministry of International Trade and Industry determined that fused silica optical fibers could transmit solar radiation effectively, that is in excess of 90% efficiency, over distances of about forty meters. U.S. Pat. No. 4,026,267 issued to Richard Coleman describes the use of optical fibers to bus concentrated energy into a residential home for use as a space heating system. However, the system described in the noted patent of Richard Coleman did not consider bussing the power to a centralized converter for the generation of electricity. None of these noted efforts were oriented towards solving the problem of packaging and aligning large concentration collectors for use in solar dynamic converters in space.